Producing disc prostheses in two or three components with which the movements of the vertebrae may be reproduced is known. When the prosthesis comprises two components, these components comprise complementary articular surfaces, providing direct jointing of one component with the other. When the prosthesis comprises three components, both components anchored at the respective vertebrae are each jointed on an intermediate sliding component, generally in polyethylene.
The existing vertebral disc prostheses, particularly those intended for cervical vertebrae, do not give complete satisfaction. Indeed, the repeated movements which they undergo, result in more or less rapid wear of the articular surfaces, which in the case of cervical disc prostheses have reduced dimensions. This wear leads to an undesirable diffusion of particles into the organism of the patient.
When the prosthesis comprises three components, there moreover exists a risk of expulsion of the intermediate component.
Further, the existing prostheses are relatively complex to make, taking into account stresses resulting from metal/metal or metal/polyethylene contacts.
Document US 2004/024460 describes a disc prosthesis comprising rigid components and a damping component interposed between these rigid components. The damping component is central and the rigid components comprise several sets of peripheral or lateral “cylinders”, indicated as reducing the tiltability of a rigid component relatively to the other. FIG. 11B shows a possibility for the “pistons” of the “cylinders” of abutting against the bottom of the “cylinders”, causing the damping component to achieve partial damping, whereas FIG. 11C shows a possibility for the “pistons” of the “cylinders” of not abutting against the bottom of the “cylinders”, causing the damping component to achieve total damping. FIGS. 22a and 22b of this document show a version of the disc illustrated in FIG. 11, in which the pistons comprise widened heads, and cylinders form internal edges, in order to form the limiting travel abutments.